The sector covered by this patent""s technique is the graphic arts and computer technology sphere, particularly in the application of colours and tonalities and in decoration.
Statement of the prior state of the art. The techniques previously known for printing with the machines available on the market generate the plates of the three basic colours and black for example, so that the basic colours and black are printed in successive impressions by the conventionally driven rotation of the screen, so that the screens thus arranged generatexe2x80x94when the sum of their colours exceeds 50% of the surface areaxe2x80x94erroneous combinations and therefore contamination of the intended colour, removing light through the invasion of the white, and with a consequent lack of accuracy in the resulting colour. This lack of light and colour contamination requires a successive correction process, in which the different combinations of colours have to be tried out without over obtaining the tonalities intended. For this reason the colour turns out to be unreal in large areas of the image, and what is more inconvenient still, it is impossible to repair by known methods on this kind of screen. Another undesired effect caused by the rotation of the screens is the appearance of what is known as the xe2x80x9cmoirexe2x80x9d pattern, through improper positioning of the screens.
Another well-known technique is the stochastic method, which consists in the arrangement of a great density of dots of a very small size, distributed to form the image, the more dots the darker this has to be. This technique obtains good results, and has the disadvantage that the dot is fixed and photolithographs cannot be touched up, and the machines and paper have to be special.
EP-A-0 321 315 consists of an apparatus for printing half tone image reproductions, which make a selection of the printing based on the intensity of the pixel to be printed and according to a pseudo-random number, which result in print or unprint of the said pixel.
There is not a definition of how to compose the colour and this system is not useful for conventional printing methods.
EP-A-0 011 722 refers to a method and device for making colour reproductions which consists of a method of obtaining a scanned image and its being said image printed by ink injection. The method allow to correct the printing units.
This method does not allow to analyze and describe the colour in an elemental area in such a way that the colour could be cleanly printed, and also does not allow to be used in conventional printing means.
EP-A-0 741 042 refers to a control of liquid-ink printing and discloses a method for avoiding redundant printing and reducing the discontinuity between pixels, substituting or modifiing the relation or proportion of ink dot prints, which shows frequently a discontinuity between pixels, and some of the pixels are frequently dotted.
This control and printing system does not give any rule for the positions or composition to the colour set in each pixel, and does not solve the obtention of a natural colour when printed in pixels, and also, as the previous documents, is not useful for conventional print systems.
The present invention consists of the arrangement of colour in each dot so that this is structured by subdivisions of the initial layout of the aforementioned dot, and the basic colours are laid out on surface in this way. It aims to provide a method for polychrome printing on diverse surfaces which provides absolute uniformity as regards the distribution of the masses of colour, avoiding the xe2x80x9cmoirexe2x80x9d effect, generating the colour as this is found on the original photograph, providing a greater luminosity and also constituting an arrangement that can be printed with the same uniformity as many times as is necessary. The treatment of the colour pigment is also expressed according to a common rule.
In this text it should be understood that we mean screens, dots, lines or reticles, even when talking of dots, for reasons of dialectic simplification.
This method consists in treating the reticle for taking and picking up colour whenever this is present, to the corresponding size, by means of mixing through joining other dots or a combination of these, without producing contamination by printing from screens in rotated positions thus generating undesired combinations.
In order to make the following explanation clearer, eight sheets of drawings are enclosed, containing twelve figures to represent the essence of this invention.
FIG. 1 shows a diagram of the colour codes.
FIG. 2 shows a basic four-colour print according to the rotation of the screens.
FIG. 3 shows a conventional basic two-colour print according to the screen rotation.
FIG. 4 shows a basic two-colour print through superimposing the corresponding chromatism in the centre of each dot.
FIG. 5 shows a random layout of the arrangement of chromatism in one dot, and the arrangement of four adjacent points of this chromatism in each set.
FIG. 6 shows an arrangement through joining up each of the dots generated according to FIG. 5.
FIG. 7 shows an application of colour on a previously existing background.
FIG. 8 shows the printing diagram of a colour on a white support.
FIG. 9 shows the printing diagram of a colour on a yellow support, for example.
FIG. 10 shows a chromatic diagram of a dot in centred proportions of colour.
FIG. 11 shows a chromatic diagram of a dot in proportions of colour forming strips.
FIG. 12 shows a chromatic diagram of a dot in greater proportions of colour than in FIG. 11, forming strips.